1. Field of the Invention
This invention relates to a process and apparatus for forming, recovering, and separating fullerenes. More particularly, this invention relates to a process and apparatus for making a mixture of impure fullerenes, transporting the mixture via a non-reactive gas to a heated filter zone, filtering out solid impurities from the vaporized fullerenes, thermally separating the fullerenes in the vapor phase, and then condensing and recovering the fullerenes.
2. Description of the Related Art
The formation of fullerene structures has been reported by the formation of soot from the evaporation of graphite electrodes in an evaporation chamber. The soot is scraped from the walls of the chamber and the fullerenes produced in the soot are separated from the remaining carbon forms therein by dissolving the fullerenes in a solvent such as benzene or toluene, and then separating this solution from the undissolved soot. The solvent is then evaporated to recover the fullerenes.
Such fullerene formation and recovery methods are described, for example, by Kratschmer et al. in "Solid C.sub.60 : A New Form of Carbon", published in Nature, Volume 247, pp 354-357, on Sep. 27, 1990; and by Y. K. Bae et al. in "Production, Characterization, and Deposition of Carbon Clusters", prepared for the Symposium on Clusters and Cluster Assembled Materials Special Session on Buckminsterfullerenes, in Boston, MA on Nov. 29, 1990, and published in The Proceedings of the 1990 Meeting of the MRS Society.
Such fullerenes, after formation and recovery by methods such as described above, are then separated from one another, if desired, i.e., purified, so that each may be independently used. Conventionally, such a separation is carried out using column chromatographic procedures.
However, while such techniques have been satisfactory for producing small quantities of fullerenes for experimental purposes, there remains a need for a process wherein larger quantities of fullerenes can be reliably produced, so that they may be utilized for commercial purposes such as, for example, in superconducting materials, in fullerene based chemicals, in polymers, etc.